Anti-IMP4 antibodies are used in the immunodetection of the protein IMP U3 small nucleolar ribonucleoprotein 4. In humans, the canonical protein has a reported length of 291 amino acid residues and a mass of 33.8 kDa. Its subcellular localization is in the nucleus. IMP4 is a known component of the 60-80S U3 small nucleolar ribonucleoprotein (U3 snoRNP). Synonyms for this target antigen include IMP4 homolog, U3 small nucleolar ribonucleoprotein, IMP4, U3 small nucleolar ribonucleoprotein, homolog, U3 snoRNP protein 4 homolog, and U3 small nucleolar ribonucleoprotein protein IMP4.